Location: Watershed Physical Processes ResearchTitle: Assessment of practices for controlling shallow valley-bottom gullies in the sub-humid Ethiopian highlands
|ADDISIE, MESERET - Bahir Dar University|
|AYNALEM, DESSALEW - Bahir Dar University|
|AYELE, GETANEH - Bahir Dar University|
|TILAHUN, SEIFU - Bahir Dar University|
|SCHMITTER, PETRA - International Water Research Institute|
|MEKURIA, WOLDE - International Water Research Institute|
|MOGES, MIKAEL - Bahir Dar University|
|STEENHUIS, TAMMO - Cornell University - New York|
Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2018
Publication Date: 3/27/2018
Citation: Addisie, M.B., Langendoen, E.J., Aynalem, D.W., Ayele, G.K., Tilahun, S.A., Schmitter, P., Mekuria, W., Moges, M.M., Steenhuis, T.S. 2018. Assessment of practices for controlling shallow valley-bottom gullies in the sub-humid Ethiopian highlands. Water. 10(4):389. 10.3390/w10040389.
Interpretive Summary: Controlling gully erosion in the sub humid northern highlands of Ethiopia remains a challenge as conventional control measures such as check dams have not been effective. Scientists from the USDA, ARS, National Sedimentation Laboratory in collaboration with researchers from Cornell University, International Water Management Institute, and Bahir Dar University, Ethiopia, conducted a four-year long study on 14 gullies in the Birr watershed to better understand the regional gully erosion processes and to prevent gully head retreat. Six gullies were used as a control and eight gullies were stabilized. The median head retreat of the control gullies was 3.6 m per year. The gully heads protected by riprap did not erode and were the most cost effective. Vegetative treatments prevented gully incision by trapping sediments but did not stop the upslope retreat. Conservation practices that lower both the water table and protect the gully heads can therefore play a key role in reducing gully expansion and soil loss due to gully erosion in the Ethiopian highlands.
Technical Abstract: Rehabilitation of gullies in developing countries is unsuccessful due to the high cost. Arresting head cuts at time of initiation will prevent large gullies from forming and is affordable. However, research on practices to arrest shallow gully heads with local materials is limited. The objective was therefore to identify cost effective shallow gully head stabilization practices. The 4-year study was conducted on 14 shallow gullies (< 3m deep) in the central Ethiopian highlands. Six gullies were used as a control. Heads in the remaining eight gullies were regraded to a 1:1 slope. Additional practices implemented were adding either riprap or vegetation or both on the regraded heads and stabilizing the gully bed downstream. Gully heads were enclosed by fencing to prohibit cattle access to the planted vegetation. The median head retreat of the control gullies was 3.6 m a-1 with a maximum of 23 m a-1. The gully heads protected by riprap did not erode and were the most cost effective. Vegetative treatments prevented gully incision by trapping sediments but did not stop the upslope retreat. Gully bed stabilization provided protection of the gully with minimal scour. The gully head remedial practices were profitable for farmers, only if the value of the hay grown on the fenced-in areas was included.